Dump H.264 data of a movie file using AVAssetReader

dump.swift

func dumpH264(_ path:URL) -> Void {
    let asset:AVURLAsset = AVURLAsset(url:path, options:nil)
    let video_tracks:Array = asset.tracks(withMediaType: AVMediaTypeVideo)
    var output:AVAssetReaderOutput? = nil
    
    do {
        try self.asset_reader = AVAssetReader.init(asset: asset)
    } catch {
        fatalError("Unable to read Asset: \(error)")
    }
    
    if let video_track = video_tracks.first {
        output = AVAssetReaderTrackOutput(track: video_track, outputSettings: nil)
        self.asset_reader!.add(output!)
        self.asset_reader!.startReading()
    }
    
    while (self.asset_reader!.status == AVAssetReaderStatus.reading) {
        if let sampleBuffer = output!.copyNextSampleBuffer() {
            if let blockBuffer = CMSampleBufferGetDataBuffer(sampleBuffer){
                let length = CMBlockBufferGetDataLength(blockBuffer)
                let tempBytes = UnsafeMutableRawPointer.allocate(bytes: length, alignedTo: 1)
                var returnedPointer: UnsafeMutablePointer<Int8>?
                
                if CMBlockBufferAccessDataBytes(blockBuffer, 0, length, tempBytes, &returnedPointer) != kCMBlockBufferNoErr {
                    break
                } else {
                    tempBytes.deallocate(bytes: length, alignedTo: 1)
                    
                    let data = Data(bytes: returnedPointer!, count: length)
                    var byteArray = [UInt8](repeating: 0x0, count: length)
                    
                    data.copyBytes(to: &byteArray, count:length)
                    for v in byteArray {
                        print(String(format: "0x%02x", v))
                    }
                }
            }
        }
    }
}